The Selkirk Glaciers are comparatively small but very numerous. They are remarkable for their purity and are not, as a rule, defaced by moraines or covered by rock debris. Particularly remarkable are the vast number of hanging glaciers. Along the heads of the high valleys they are found lining the sides, and are strikingly beautiful in the labyrinthine structure of their crevassed surfaces, which from a distance resemble a creamy film of lace-work enshrouding bare rock. Compared with the great glaciers of Alaska, of the Himalaya, and of other great mountain systems, they are puny; but even so, they have distinctive features all their own that give them a prominent place in the study of those parts of the earth that are covered by ice.
A NOTE ON THE GEOLOGY OF THE SELKIRK MOUNTAINS.
The Geological Survey of Canada has done very little work in the Selkirk Mountains, and the only report on them was made by Dr. Dawson about twenty years ago. Following the C.P.R. from west to east there are first about seventeen miles of very ancient rocks, granites and gneisses of the Archaean. These rocks, with the nearer parts of the Gold Range to the west, represent the old nucleus or "protaxis" of the western ranges. They probably formed an important mountain range in the earliest times, but being so old, have suffered the penalty of age in mountains and have been greatly cut down.
Following the granites, eastwards there are 15,000 feet of dark slate and schist, once muddy sediments on a sea bottom, now thrown into folds, first a syncline or downward fold, afterwards an anticline or upward fold. Then come lighter colored series of quartzites and conglomerates, often schistose with the shimmer of mica scales. Near the summit these rocks make a syncline, but toward Beaver Creek they have been bent into an anticline and broken across by a great fault. The thickness of these rocks Dr. Dawson puts at 25,000 feet.
Coming out towards Donald there are later rocks (Cambro-Silurian) also folded and transformed largely into lustrous slates. Fossils are so rarely found in the Selkirks that the age of these thick deposits is quite uncertain. Dr. Dawson calls everything Cambrian between the granite and the eastern Cambro-Silurian. The granite and gneiss of the western Selkirks are very ancient eruptive rocks, highly crystalline and formed far below the surface. It is rather remarkable that there are very few undoubted eruptive rocks farther east and none along the line of the railway. In the Gold Range to the west there were great volcanic eruptions with lava shoots and thick beds of ashes after the Selkirks had been elevated, and there are important volcanic areas in the southern Selkirks, toward the Boundary.
As the Selkirks are a very old range, far older than the Rockies, they have undergone much destruction, and the great glaciers of the Ice Age had much to do with the moulding of the slopes and valleys, and the carving of the beautiful lake basins. (Dr. A. P. Coleman, in the Canadian Alpine Journal.)
